Carbon steel is broken down into four classes based on carbon content:

Low-carbon steel:

0.05 to 0.25% carbon content.

Medium-carbon steel:

Approximately 0.3-0.6% carbon content. Balances ductility and strength and has good wear resistance; used for large parts, forging and automotive components.

High-carbon steel:

Approximately 0.6–1.0% carbon content.Very strong, used for springs, swords, and high-strengthwires.

Ultra-high-carbon steel:

Approximately 3.25–4.0% carbon content. Steels that can be tempered to great hardness. Used for special purposes like (non-industrial-purpose) knives, axles or punches. Most steels with more than 2.5% carbon content are made using powder metallurgy.